1. Field of the Invention
The present invention relates to a method for manufacturing a liquid discharge head which discharges liquid droplets, and in particular, to a method for manufacturing an ink jet recording head which records on a recording medium by discharging ink droplets. More specifically, the present invention relates to a method for manufacturing an ink jet recording head in which nozzles that can discharge liquid droplets having multiple liquid droplet sizes are configured on the same substrate in order to perform high-speed and high-quality printing.
2. Description of the Related Art
Conventionally, as disclosed in U.S. Pat. No. 5,478,606, for example, a liquid discharge head is manufactured by the following steps. First, a soluble photosensitive resin is patterned into a liquid flow path mold on a substrate on which a discharge energy generating element is formed. Next, a photosensitive cover resin layer that will serve as a nozzle member is applied on the substrate so as to cover this mold pattern, and a liquid discharge port communicating with the mold pattern is formed on the cover resin layer. Subsequently, a liquid supply port is formed by etching so as to penetrate from the substrate back side, and the photosensitive resin used in the mold pattern is removed, to thereby manufacture the liquid discharge head. According to this manufacturing method, since a semiconductor photolithography method is used, micro-fabrication to form the liquid flow paths, discharge ports and the like very precisely can be achieved.
Here, examples of liquid discharge heads include heads that have a greater amount of ink storage by making a flow path distance between the discharge energy generating element and the discharge port longer, and heads that have a stable liquid droplet size by making a flow path distance between the discharge energy generating element and the discharge port shorter. Heads having a greater amount of ink storage can perform solid printing with large dots efficiently and quickly. Heads having a stable liquid droplet size can achieve higher quality.
Accordingly, to achieve both high speed and high quality, U.S. Patent Application Publication No. 2002/0041310 discloses a liquid discharge head in which different kinds of nozzles are formed on a single substrate in order to discharge ink droplets with different sizes. Furthermore, U.S. Pat. No. 7,198,353 discloses a liquid discharge head having orifice plates with different thicknesses on the same substrate. In addition, Japanese Patent Application Laid-Open No. 2007-125810 discloses a method for manufacturing a liquid discharge head having orifice plates with different thicknesses in order to discharge an ink in different amounts (or different droplet sizes) from the same ink supply port. In Japanese Patent Application Laid-Open No. 2007-125810, the liquid discharge head is manufactured by providing a difference of the film thickness between the orifice portions of a small liquid droplet nozzle and a large liquid droplet nozzle by forming a height adjustment member on the ink flow path pattern on the large liquid droplet nozzle side, and using a photolithography method.
Thus, in order for a liquid discharge head to provide the printing quality of small liquid droplet size while being capable of keeping the discharge amount of large liquid droplet size, it is effective to configure a liquid discharge head such that it has on the same substrate nozzles capable of discharging both large and small size liquid droplets.
However, when forming nozzles having different liquid droplet sizes on the same substrate, in terms of manufacturing method, it is difficult to simultaneously form the orifice plates for the small liquid droplet nozzles and the large liquid droplet nozzles. Conventionally, although a laminating method has been used, it is difficult to control the distortion and positional misalignment that occur during the laminating, which can result in that printing quality is not maintained.
Furthermore, in the method disclosed in Japanese Patent Application Laid-Open No. 2007-125810, it is difficult to control the thickness of the orifice plates for the small liquid droplet nozzles when the height of the height adjustment member is increased, so that the problem of being unable to maintain printing quality can arise.